1,674 research outputs found
‘‘There’s so much more to it than what I initially thought’’: Stepping into researchers’ shoes with a class activity in a first year psychology survey course
In psychology, it is widely agreed that research methods, although central to the discipline, are particularly challenging to learn and teach, particularly at introductory level. This pilot study explored the potential of embedding a student-conducted research activity in a one-semester undergraduate Introduction to Psychology survey course, with the aims of (a) engaging students with the topic of research methods; (b) developing students’ comprehension and application of research methods concepts; and (c) building students’ ability to link research with theory. The research activity explored shoe ownership, examining gender differences and relationships with age, and linking to theories of gender difference and of consumer identity. The process of carrying out the research and reflecting on it created a contextualized, active learning environment in which students themselves raised many issues that research methods lectures seek to cover. Students also wrote richer assignments than standard first year mid-term essay
Helicopter tail rotor thrust and main rotor wake coupling in crosswind flight
The tail rotor of a helicopter with a single main rotor configuration can experience a significant reduction in thrust when the aircraft operates in crosswind flight. Brown’s vorticity transport model has been used to simulate a main rotor and tail rotor system translating at a sideslip angle that causes the tail rotor to interact with the main rotor tip vortices as they propagate downstream at the lateral extremities of the wake. The tail rotor is shown to exhibit a distinct directionally dependent mode during which tail rotors that are configured so that the blades travel forward at the top of the disk develop less thrust than tail rotors with the reverse sense of rotation. The range of flight speeds over which this mode exists is shown to vary considerably with the vertical location of the tail rotor. At low flight speeds, the directionally dependent mode occurs because the tail rotor is immersed within not only the downwash from the main rotor but also the rotational flow associated with clusters of largely disorganized vorticity within the main rotor wake. At higher flight speeds, however, the tail rotor is immersed within a coherent supervortex that strongly influences the velocity field surrounding the tail rotor
A technique for short‐term warning of solar energetic particle events based on flare location, flare size, and evidence of particle escape
We have developed a technique to provide short‐term warnings of solar energetic proton (SEP) events that meet or exceed the Space Weather Prediction Center threshold of J (>10 MeV) = 10 pr cm−2 s−1 sr−1. The method is based on flare location, flare size, and evidence of particle acceleration/escape as parameterized by flare longitude, time‐integrated soft X‐ray intensity, and time‐integrated intensity of type III radio emission at ∼1 MHz, respectively. In this technique, warnings are issued 10 min after the maximum of ≥M2 soft X‐ray flares. For the solar cycle 23 (1995–2005) data on which it was developed, the method has a probability of detection of 63% (47/75), a false alarm rate of 42% (34/81), and a median warning time of ∼55 min for the 19 events successfully predicted by our technique for which SEP event onset times were provided by Posner (2007). These measures meet or exceed verification results for competing automated SEP warning techniques but, at the present stage of space weather forecasting, fall well short of those achieved with a human (aided by techniques such as ours) making the ultimate yes/no SEP event prediction. We give some suggestions as to how our method could be improved and provide our flare and SEP event database in the auxiliary material to facilitate quantitative comparisons with techniques developed in the future
Ethics, politics and migration: Public debates on the free movement of Romanians and Bulgarians in the UK, 2006–2013
Public debates on immigration have become the subject of much concern, particularly in the UK. This article applies an ethical lens to assess changes in public debates over intra-EU migration in six UK national newspapers during 2006 and 2013. It finds an almost complete dominance of communitarian justifications, mainly based on welfare chauvinism, but a notable increase in security-related arguments and a decrease in economic nationalist ideas. Alternative cosmopolitan arguments about immigration go from rare to virtually absent. The discussion links these shifts to a failure of the UK centre-left to overcome historic difficulties in presenting a coherent narrative on immigration policy
Melanoma cells break down LPA to establish local gradients that drive chemotactic dispersal.
The high mortality of melanoma is caused by rapid spread of cancer cells, which occurs unusually early in tumour evolution. Unlike most solid tumours, thickness rather than cytological markers or differentiation is the best guide to metastatic potential. Multiple stimuli that drive melanoma cell migration have been described, but it is not clear which are responsible for invasion, nor if chemotactic gradients exist in real tumours. In a chamber-based assay for melanoma dispersal, we find that cells migrate efficiently away from one another, even in initially homogeneous medium. This dispersal is driven by positive chemotaxis rather than chemorepulsion or contact inhibition. The principal chemoattractant, unexpectedly active across all tumour stages, is the lipid agonist lysophosphatidic acid (LPA) acting through the LPA receptor LPAR1. LPA induces chemotaxis of remarkable accuracy, and is both necessary and sufficient for chemotaxis and invasion in 2-D and 3-D assays. Growth factors, often described as tumour attractants, cause negligible chemotaxis themselves, but potentiate chemotaxis to LPA. Cells rapidly break down LPA present at substantial levels in culture medium and normal skin to generate outward-facing gradients. We measure LPA gradients across the margins of melanomas in vivo, confirming the physiological importance of our results. We conclude that LPA chemotaxis provides a strong drive for melanoma cells to invade outwards. Cells create their own gradients by acting as a sink, breaking down locally present LPA, and thus forming a gradient that is low in the tumour and high in the surrounding areas. The key step is not acquisition of sensitivity to the chemoattractant, but rather the tumour growing to break down enough LPA to form a gradient. Thus the stimulus that drives cell dispersal is not the presence of LPA itself, but the self-generated, outward-directed gradient
SeaWiFS Technical Report Series
Two issues regarding primary productivity, as it pertains to the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Program and the National Aeronautics and Space Administration (NASA) Mission to Planet Earth (MTPE) are presented in this volume. Chapter 1 describes the development of a science plan for deriving primary production for the world ocean using satellite measurements, by the Ocean Primary Productivity Working Group (OPPWG). Chapter 2 presents discussions by the same group, of algorithm classification, algorithm parameterization and data availability, algorithm testing and validation, and the benefits of a consensus primary productivity algorithm
Temperature Modulates Coccolithophorid Sensitivity of Growth, Photosynthesis and Calcification to Increasing Seawater pCO2
Increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by
driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and
seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for
possible synergistic effects we exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO2
gradient ranging from ,0.5–250 mmol kg21 (i.e. ,20–6000 matm pCO2) at three different temperatures (i.e. 10, 15, 20uC for
E. huxleyi and 15, 20, 25uC for G. oceanica). Both species showed CO2-dependent optimum-curve responses for growth,
photosynthesis and calcification rates at all temperatures. Increased temperature generally enhanced growth and
production rates and modified sensitivities of metabolic processes to increasing CO2. CO2 optimum concentrations for
growth, calcification, and organic carbon fixation rates were only marginally influenced from low to intermediate
temperatures. However, there was a clear optimum shift towards higher CO2 concentrations from intermediate to high
temperatures in both species. Our results demonstrate that the CO2 concentration where optimum growth, calcification and
carbon fixation rates occur is modulated by temperature. Thus, the response of a coccolithophore strain to ocean
acidification at a given temperature can be negative, neutral or positive depending on that strain’s temperature optimum.
This emphasizes that the cellular responses of coccolithophores to ocean acidification can only be judged accurately when
interpreted in the proper eco-physiological context of a given strain or species. Addressing the synergistic effects of
changing carbonate chemistry and temperature is an essential step when assessing the success of coccolithophores in the
future ocean
Factors regulating the Great Calcite Belt in the Southern Ocean and its biogeochemical significance
The Great Calcite Belt (GCB) is a region of elevated surface reflectance in the Southern Ocean (SO) covering ~16% of the global ocean and is thought to result from elevated, seasonal concentrations of coccolithophores. Here we describe field observations and experiments from two cruises that crossed the GCB in the Atlantic and Indian sectors of the SO. We confirm the presence of coccolithophores, their coccoliths, and associated optical scattering, located primarily in the region of the subtropical, Agulhas, and Subantarctic frontal regions. Coccolithophore-rich regions were typically associated with high-velocity frontal regions with higher seawater partial pressures of CO2 (pCO2) than the atmosphere, sufficient to reverse the direction of gas exchange to a CO2 source. There was no calcium carbonate (CaCO3) enhancement of particulate organic carbon (POC) export, but there were increased POC transfer efficiencies in high-flux particulate inorganic carbon regions. Contemporaneous observations are synthesized with results of trace-metal incubation experiments, 234Th-based flux estimates, and remotely sensed observations to generate a mandala that summarizes our understanding about the factors that regulate the location of the GCB
Lymph Node Negative Colorectal Cancers with Isolated Tumor Deposits Should Be Classified and Treated As Stage III
BACKGROUND: The prognostic role of pericolic or perirectal isolated tumor deposits (ITDs) in node-negative colorectal cancer (CRC) patients is unclear. Rules to define ITDs as regional lymph node metastases changed in subsequent editions of the TNM staging without substantial evidence. Aim of this study was to investigate the correlation between ITDs and disease recurrence in stage II and III CRC patients. MATERIALS AND METHODS: The medical files of 870 CRC patients were reviewed. Number, size, shape, and location pattern of all ITDs in node-negative patients were examined in relation to involvement of vascular structures and nerves. The correlation between ITDs and the development of recurrent disease was investigated. RESULTS: Disease recurrence was observed in 50.0% of stage II patients with ITDs (13 of 26), compared with 24.4% of stage II patients without ITDs (66 of 270) (P <.01). Disease-free survival of ITD-positive stage II patients was comparable with that of stage III patients. Also within stage III, more recurrences were observed in ITD-positive patients compared with ITD-negative patients (65.1 vs. 39.1%, respectively). No correlation was found between size of ITDs and disease recurrence. More recurrences were seen in patients with irregularly shaped ITDs compared with patients with 1 or more smooth ITDs present. CONCLUSIONS: Because of the high risk of disease recurrence, all node-negative stage II patients with ITDs, regardless of size and shape, should be classified as stage III, for whom adjuvant chemotherapy should be considere
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